1. Field of the Invention
The present invention relates to a color liquid crystal display device used as display device for consumer and industrial information appliances such as word processor and personal computer, or as display device for liquid crystal television or the like.
2. Description of the Related Art
FIG. 8 is a sectional view of a conventional color liquid crystal display device 50. A liquid crystal cell 51 for composing the color liquid crystal display device 50 is basically composed of a pair of light permeable glass substrates 52, 53, and a nematic liquid crystal layer 54 interposing between these glass substrates 52, 53. A transparent electrode 55 and an orientation film 56 are sequentially formed on a surface 52a of one glass substrate 52 confronting the other glass substrate 53.
On a surface 53a of the other glass substrate 53 confronting the glass substrate 52, a color filter 57, an overcoat film 58, a transparent electrode 59, and an orientation film 60 are sequentially formed. A seal member 62 is annularly interspacing the mutually confronting surfaces 52a, 53a of the glass substrates 52, 53, and a mixed liquid crystal is injected in a space 61 between the surfaces 52a, 53a, thereby forming the nematic liquid crystal layer 54.
On the transparent electrode 59 in an electrode terminal part 63 of thus formed liquid crystal cell 51, a lead 64 of TAB (tape automated bonding) for input of driving signal is compression-bonded, and a connection terminal is formed.
Thus, in the conventional color liquid crystal display device 50, since it is difficult to form the transparent electrode 59 directly on the color filter 57, in order to enhance a smoothness and adhesion, the overcoat film 58 is formed on the entire of the surface 53a of the glass substrate 53 on which the color filter 57 is formed, and then the transparent electrode 59 is formed on the overcoat film 58.
However, the overcoat film 58 is lower in strength as compared with the glass substrate 53 and transparent electrode 59 and is vulnerable to flaw and impact, and moreover the adhesion of the overcoat film 58 and the surface 53a of the glass substrate 53 are easily affected by the residue of the glass substrate 53 which is the base surface, and fluctuations of the adhesion are significant.
Therefore, in the manufacturing process, for example, disconnection may occur in the transparent electrode 59 of the electrode, terminal part 63, or peeling may occur between the overcoat-film 58 and the surface 53a of the glass substrate 53 in the region of the seal member 62 disposed on the glass substrate 53 through the transparent electrode 59 and overcoat film 58, which is a cause to lower the productivity and reliability. If the lead 64 is peeled off the glass substrate 53 together with the transparent electrode 59 and overcoat film 58 in the electrode terminal part 63, or if peeled off with a part of the overcoat film 58 and transparent electrode 59 left over on the glass surface 53, the lead 64 cannot be compression-bonded to the transparent electrode 59 again at the same position, which requires repairing for compression-bonding of the lead 64 again on the transparent electrode 59 through the overcoat film 58 remaining on the glass substrate 53. Allowing for such repair, the electrode terminal part 63 must be set longer than the length necessary for compression-bonding the lead 64.
Furthermore, in the region 65 of the seal member 62 disposed on the glass substrate 53 through the transparent electrode 59 and overcoat film 58, a fluctuation may occur in the film thickness D2 of the overcoat film 58, and accordingly the cell gap near the seal member 62 may be uneven, which may cause lowering of the display quality such as light penetration and uneven lighting.